Barack Obama made an unscheduled stop Wednesday at a downtown building that houses the law firm of one member of his vice presidential search team.

Aides said the likely Democratic nominee had private meetings planned while in Washington, but declined to provide additional details, including whether Obama was meeting with Eric Holder, a partner at Covington and Burling who is helping the candidate vet potential running mates.

Obama exited two hours and 20 minutes later. Asked whom he was meeting with, Obama said, “I’m not going to tell you.” He was accompanied by campaign manager David Plouffe.

The firm is located just blocks from the White House that Obama hopes to occupy come January.

Obama’s entourage, including a small contingent of reporters, left the Renaissance Mayflower Hotel around 9:30 a.m., presumably to head to Capitol Hill so the Illinois senator could vote on a couple of bills.

A few minutes later and surprising even some of his aides, the motorcade pulled over and Obama entered the building from a back door with a sign that said “Tenant Entrance Only.” A top adviser, David Axelrod, accompanied Obama.